Thermoplastic melt-mixed composition with epoxy-amino acid compound heat stabilizer and processes for their preparation

ABSTRACT

Disclosed is a thermoplastic melt-mixed composition including: a) a polyamide resin; b) a poly(amino acid)-polyol compound provided by reacting: b1) one or more amino acids selected from the group consisting of primary amino acids and secondary amino acids and combinations of these; the amino acid having no more than one hydroxyl group; and b2) one or more polyepoxy compound comprising at least two or more epoxy groups; the poly(amino acid)-polyol compound having a range of at least 10 percent conversion of epoxy equivalents of component (b1) up to, but excluding, the gel point of the components b1) and b2) and c) reinforcing agent; and, optionally, d) polymeric toughener; and f) further additives. Processes for making the composition are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/658,995, filed Jun. 13, 2012, now pending.

FIELD OF INVENTION

The present invention relates to the field of polyamide compositionshaving improved long-term high temperature aging characteristics.

BACKGROUND OF INVENTION

High temperature resins based on polyamides possess desirable chemicalresistance, processability and heat resistance. This makes themparticularly well suited for demanding high performance automotive andelectrical/electronics applications. There is a current and generaldesire in the automotive field to have high temperature resistantstructures since temperatures higher than 150° C., even higher than 200°C., are often reached in under-hood areas of automobiles. When plasticparts are exposed to such high temperatures for a prolonged period, suchas in automotive under-the-hood applications or inelectrical/electronics applications, the mechanical properties generallytend to decrease due to the thermo-oxidation of the polymer. Thisphenomenon is called heat aging.

In an attempt to improve heat aging characteristics, polyhydric alcoholshave been found to give significantly improved heat agingcharacteristics as disclosed in US patent application publication US2010-0029819 A1 (Palmer et al). However, molded articles derived fromthe polyamide compositions comprising the polyhydric alcohols have atendency to undergo surface whitening upon aging at high humidity; whichis an undesirable feature for many applications.

There remains a need for thermoplastic compositions that are suitablefor manufacturing articles that exhibit good mechanical properties afterlong-term high temperature exposure and have desirable visualproperties; that is, exhibit no whitening or a low degree of whitening,upon aging at high humidity.

EP 1041109 discloses a polyamide composition comprising a polyamideresin, a polyhydric alcohol having a melting point of 150 to 280° C.,that has good fluidity and mechanical strength and is useful ininjection welding techniques.

Pending U.S. patent application U.S. Ser. No. 13/359,885, filed Jan. 27,2012, discloses a thermoplastic molding composition including an aminoacid heat stabilizer having two or more carboxylic acids.

Pending U.S. patent application U.S. Ser. No. 13/359,784, filed Jan. 27,2012, discloses a thermoplastic molding composition including ahydroxylamino acid heat stabilizer having one or more hydroxyl groups.

KR 20020010356 A discloses a polyamide composition comprising apolyamide resin, a plasticizer selected from the group consisting ofplasticizers including lactam-based plasticizer and an epoxy resin.

U.S. Pat. No. 5,605,945 discloses a polyamide molding composition withincreased viscosity, high thermal stability and favorable mechanicalproperties comprising a polyamide resin and a diepoxide.

U.S. Pat. No. 4,315,086 discloses a resin composition comprising apoly(phenyl oxide)/polyamide, and a member select from the groupconsisting of A) liquid diene polymers, B) epoxy compounds and C)compounds having in the molecule both an ethylene carbon-carbon doublebond or a carbon-carbon triple bond and a group including an carboxylicacid group.

US patent publication 2005/0228109 discloses a thermoplastic compositioncomprising poly(phenylene oxide), polyamide, an unsaturated carboxylicacid copolymer and/or a polymer with pendant epoxy groups.

SUMMARY

One embodiment of the invention is a thermoplastic melt-mixedcomposition comprising:

-   -   a) 15 to 89.5 weight percent of a poly(hexamethylene        hexanediamide);    -   b) 0.5 to 10 weight percent of a poly(amino acid)-polyol        compound provided by reacting:        -   b1) 90 to 10 weight percent one or more amino acids selected            from the group consisting of primary amino acids and            secondary amino acids and combinations of these; said amino            acid having no more than one hydroxyl group; and        -   b2) 10 to 90 weight percent of one or more polyepoxy            compound comprising at least two or more epoxy groups; the            polyepoxy compound having a epoxide equivalent weight of 43            to 4000 g/equivalent as determined by calculation, or if the            polyepoxy compound is an oligomer, by titration using ASTM            D1652-11 method; and a number average molecular weight            (M_(n)) of less than 8000;    -   wherein the weight percent of component b) is based on the total        weight of b1) and b2); said poly(amino acid)-polyol compound        having a range of at least 10 percent conversion of epoxy        equivalents of component (b1) up to, but excluding, the gel        point of the components b1) and b2) as determined with ¹H NMR        analysis of the poly(amino acid)-polyol;    -   c) 10 to 60 weight percent of reinforcing agent;    -   d) 0 to 30 weight percent polymeric toughener; and    -   e) 0 to 10 weight percent further additives;        wherein the weight percentages a), b), c), d), and e) are based        on the total weight of the thermoplastic melt-mixed composition.

Another embodiment is a process for providing a thermoplastic melt-mixedcomposition comprising:

-   -   A) melt-blending:    -   a) 15 to 89.5 weight percent of poly(hexamethylene        hexanediamide);    -   b) 0.5 to 10 weight percent of a poly(amino acid)-polyol        compound provided by reacting:        -   b1) 90 to 10 weight percent one or more amino acids selected            from the group consisting of primary amino acids and            secondary amino acids and combinations of these; said amino            acid having no more than one hydroxyl group; and        -   b2) 10 to 90 weight percent of a polyepoxy compound            comprising at least two or more epoxy groups; the polyepoxy            compound having a epoxide equivalent weight of 43 to 4000            g/equivalent as determined by calculation, or if the            polyepoxy compound is an oligomer, by titration using ASTM            D1652-11 method; and a number average molecular weight            (M_(n)) of less than 8000;    -   c) 10 to 60 weight percent of reinforcing agent;    -   d) 0 to 30 weight percent polymeric toughener; and    -   e) 0 to 10 weight percent further additives;        to provide said thermoplastic melt-mixed composition; wherein        the weight percent of b) is based on the total weight of b1) and        b2); said poly(amino acid)-polyol compound having a range of at        least 10 percent conversion of epoxy equivalents of component        b1) up to, but excluding, the gel point of the components b1)        and b2) as determined with ¹H NMR analysis of the poly(amino        acid)-polyol compound.

Another embodiment is a method for improving tensile strength retentionof a thermoplastic melt-mixed composition under air oven ageing (AOA)conditions comprising:

-   -   melt-blending:    -   a) 15 to 89.5 weight percent of poly(hexamethylene        hexanediamide);    -   b) 0.5 to 10 weight percent of a poly(amino acid)-polyol        compound provided by reacting:        -   b1) 90 to 10 weight percent one or more amino acids selected            from the group consisting of primary amino acids and            secondary amino acids and combinations of these; said amino            acid having no more than one hydroxyl group; and        -   b2) 10 to 90 weight percent of a polyepoxy compound            comprising at least two or more epoxy groups; the polyepoxy            compound having a epoxide equivalent weight of 43 to 4000            g/equivalent as determined by calculation, or if the            polyepoxy compound is an oligomer, by titration using ASTM            01652-11 method; and a number average molecular weight            (M_(n)) of less than 8000;    -   c) 10 to 60 weight percent of reinforcing agent;    -   d) 0 to 30 weight percent polymeric toughener; and    -   e) 0 to 10 weight percent further additives;        to provide said thermoplastic melt-mixed composition; wherein        the weight percent of b) is based on the total weight of b1) and        b2); said poly(amino acid)-polyol compound having a range of at        least 10 percent conversion of epoxy equivalents of        component (a) up to, but excluding, the gel point of the        components a) and b) as determined with ¹H NMR analysis of the        poly(amino acid)-polyol compound; wherein 2 mm thick test bars,        prepared from said melt-mixed composition and tested according        to ISO 527-2/1BA, and exposed at a test temperature of 230° C.        for a test period of 1000 hours, in an atmosphere of air, have        on average, a retention of tensile strength of at least 25        percent, as compared with that of an unexposed control of        identical composition and shape; and wherein the polyamide resin        is poly(hexamethylene hexanediamide).

DETAILED DESCRIPTION

Herein melting points and glass transitions are as determined withdifferential scanning calorimetry (DSC) at a scan rate of 10° C./min inthe first heating scan, wherein the melting point is taken at themaximum of the endothermic peak and the glass transition, if evident, isconsidered the mid-point of the change in enthalpy.

For the purposes of the description, unless otherwise specified,“high-temperature” means a temperature at or higher than 210° C., andmost preferably at or higher than 230° C.

In the present invention, unless otherwise specified, “long-term” refersto an aging period equal or longer than 500 hrs.

As used herein, the term “high heat stability”, as applied to thepolyamide composition disclosed herein or to an article made from thecomposition, refers to the retention of physical properties (forinstance, tensile strength) of 2 mm thick molded test bars consisting ofthe polyamide composition that are exposed to air oven aging (AOA)conditions at a test temperature at 230° C. for a test period of atleast 500 h, in an atmosphere of air, and then tested according to ISO527-2/1 BA method. The physical properties of the test bars are comparedto that of unexposed controls that have identical composition and shape,and are expressed in terms of “% retention”. In a preferred embodimentthe test temperature is at 230° C., the test period is at 1000 hours andthe exposed test bars have a % retention of tensile strength of at least40%. Herein “high heat stability” means that said molded test bars, onaverage, meet or exceed a retention for tensile strength of 40% whenexposed at a test temperature at 230° C. for a test period of at least1000 h. Compositions exhibiting a higher retention of physicalproperties for a given exposure temperature and time period have betterheat stability.

The terms “at 170° C.,” “at 210° C.” and “at 230° C.” refer to thenominal temperature of the environment to which the test bars areexposed; with the understanding that the actual temperature may vary by+/−2° C. from the nominal test temperature.

One embodiment of the invention is a thermoplastic melt-mixedcomposition comprising:

a) 15 to 89.5 weight percent of a polyamide resin;

b) 0.5 to 10 weight percent of a poly(amino acid)-polyol compoundprovided by reacting:

b1) 90 to 10 weight percent one or more amino acids selected from thegroup consisting of primary amino acids and secondary amino acids andcombinations of these; said amino acid having no more than one hydroxylgroup; and

b2) 10 to 90 weight percent of one or more polyepoxy compound comprisingat least two or more epoxy groups; the polyepoxy compound having aepoxide equivalent weight of 43 to 4000 g/equivalent as determined bycalculation, or if the polyepoxy compound is an oligomer, by titrationusing ASTM 01652-11 method; and a number average molecular weight (Mn)of less than 8000, as determined with size exclusion chromatography;

wherein the weight percent of component b) is based on the total weightof b1) and b2); said poly(amino acid)-polyol compound having a range ofat least 10 percent conversion of epoxy equivalents of component (b1) upto, but excluding, the gel point of the components b1) and b2) asdetermined with ¹H NMR analysis of the poly(amino acid)-polyol;

c) 10 to 60 weight percent of reinforcing agent;

d) 0 to 30 weight percent polymeric toughener; and

e) 0 to 10 weight percent further additives;

wherein the weight percentages a), b), c), d), and e) are based on thetotal weight of the thermoplastic melt-mixed composition.

Polyamide Resin

The thermoplastic polyamide compositions of various embodiments of theinvention comprise a polyamide resin. The polyamide resins arecondensation products of one or more dicarboxylic acids and one or morediamines, and/or one or more aminocarboxylic acids, and/or ring-openingpolymerization products of one or more cyclic lactams. Suitable cycliclactams are caprolactam and laurolactam. Polyamides may be fullyaliphatic or semi-aromatic.

Fully aliphatic polyamides are formed from aliphatic and alicyclicmonomers such as diamines, dicarboxylic acids, lactams, aminocarboxylicacids, and their reactive equivalents. A suitable aminocarboxylic acidis 11-aminododecanoic acid. Suitable lactams are caprolactam andlaurolactam. In the context of this invention, the term “fully aliphaticpolyamide” also refers to copolymers derived from two or more suchmonomers and blends of two or more fully aliphatic polyamides. Linear,branched, and cyclic monomers may be used.

Carboxylic acid monomers comprised in the fully aliphatic polyamidesinclude, is but are not limited to aliphatic carboxylic acids, such asfor example adipic acid (C6), pimelic acid (C7), suberic acid (C8),azelaic acid (C9), decanedioic acid (C10), dodecanedioic acid (C12),tridecanedioic acid (C13), tetradecanedioic acid (C14), pentadecanedioicacid (C15), hexadecanedioic acid (C16) and octadecanedioic acid (C18).Diamines can be chosen among diamines having four or more carbon atoms,including, but not limited to tetramethylene diamine, hexamethylenediamine, octamethylene diamine, decamethylene diamine, dodecamethylenediamine, 2-methylpentamethylene diamine, 2-ethyltetramethylene diamine,2-methyloctamethylenediamine; trimethylhexamethylenediamine,meta-xylylene diamine, and/or mixtures thereof.

The semi-aromatic polyamide is a homopolymer, a copolymer, a terpolymeror more advanced polymers formed from monomers containing aromaticgroups. One or more aromatic carboxylic acids may be terephthalate or amixture of terephthalate with one or more other carboxylic acids, suchas isophthalic acid, phthalic acid, 2-methyl terephthalic acid andnaphthalic acid. In addition, the one or more aromatic carboxylic acidsmay be mixed with one or more aliphatic dicarboxylic acids, as disclosedabove. Alternatively, an aromatic diamine such as meta-xylylene diamine(MXD) can be used to provide a semi-aromatic polyamide, an example ofwhich is MXD6, a homopolymer comprising MXD and adipic acid.

Preferred polyamides disclosed herein are homopolymers or copolymerswherein the term copolymer refers to polyamides that have two or moreamide and/or diamide molecular repeat units. The homopolymers andcopolymers are identified by their respective repeat units. Forcopolymers disclosed herein, the repeat units are listed in decreasingorder of mole % repeat units present in the copolymer. The followinglist exemplifies the abbreviations used to identify monomers and repeatunits in the homopolymer and copolymer polyamides (PA):

-   HMD hexamethylene diamine (or 6 when used in combination with a    diacid)-   T Terephthalic acid-   AA Adipic acid-   DMD Decamethylenediamine-   -Caprolactam-   DDA Decanedioic acid-   DDDA Dodecanedioic acid-   TDDA Tetradecanedioic acid-   HDDA Hexadecanedioic acid-   ODDA Octadecanedioic acid-   I Isophthalic acid-   MXD meta-xylylene diamine-   TMD 1,4-tetramethylene diamine-   4T polymer repeat unit formed from TMD and T-   6T polymer repeat unit formed from HMD and T-   DT polymer repeat unit formed from 2-MPMD and T-   MXD6 polymer repeat unit formed from MXD and AA-   66 polymer repeat unit formed from HMD and AA-   10T polymer repeat unit formed from DMD and T-   410 polymer repeat unit formed from TMD and DDA-   510 polymer repeat unit formed from 1,5-pentanediamine and DDA-   610 polymer repeat unit formed from HMD and DDA-   612 polymer repeat unit formed from HMD and DDDA-   614 polymer repeat unit formed from HMD and TDDA-   616 polymer repeat unit formed from HMD and HDDA-   618 polymer repeat unit formed from HMD and ODDA-   6 polymer repeat unit formed from    -caprolactam-   11 polymer repeat unit formed from 11-aminoundecanoic acid-   12 polymer repeat unit formed from 12-aminododecanoic acid

Note that in the art the term “6” when used alone designates a polymerrepeat unit formed from

-caprolactam. Alternatively “6” when used in combination with a diacidsuch as T, for instance 6T, the “6” refers to HMD. In repeat unitscomprising a diamine and diacid, the diamine is designated first.Furthermore, when “6” is used in combination with a diamine, forinstance 66, the first “6” refers to the diamine HMD, and the second “6”refers to adipic acid. Likewise, repeat units derived from other aminoacids or lactams are designated as single numbers designating the numberof carbon atoms.

In one embodiment the polyamide composition comprises a one or morepolyamides selected from the group consisting of

-   -   Group (I) polyamides having a melting point of less than 210°        C., and comprising an aliphatic or semiaromatic polyamide        selected from the group is consisting of poly(pentamethylene        decanediamide) (PA510), poly(pentamethylene dodecanediamide)        (PA512), poly(ε-caprolactam/hexamethylene hexanediamide)        (PA6/66), poly(ε-caprolactam/hexamethylene decanediamide)        (PA6/610), poly(ε-caprolactam/hexamethylene dodecanediamide)        (PA6/612), poly(hexamethylene tridecanediamide) (PA613),        poly(hexamethylene pentadecanediamide) (PA615),        poly(ε-caprolactam/tetramethylene terephthalamide) (PA6/4T),        poly(ε-caprolactam/hexamethylene terephthalamide) (PA6/6T),        poly(ε-caprolactam/decamethylene terephthalamide) (PA6/10T),        poly(ε-caprolactam/dodecamethylene terephthalamide) (PA6/12T),        poly(hexamethylene decanediamide/hexamethylene terephthalamide)        (PA610/6T), poly(hexamethylene dodecanediamide/hexamethylene        terephthalamide) (PA612/6T), poly(hexamethylene        tetradecanediamide/hexamethylene terephthalamide) (PA614/6T),        poly(ε-caprolactam/hexamethylene isophthalamide/hexamethylene        terephthalamide) (PA6/61/6T), poly(ε-caprolactam/hexamethylene        hexanediamide/hexamethylene decanediamide) (PA6/66/610),        poly(ε-caprolactam/hexamethylene hexanediamide/hexamethylene        dodecanediamide) (PA6/66/612), poly(ε-caprolactam/hexamethylene        hexanediamide/hexamethylene decanediamide/hexamethylene        dodecanediamide) (PA6/66/610/612), poly(2-methylpentamethylene        hexanediamide/hexamethylene hexanediamide/hexamethylene        terephthamide) (PA D6166/6T), poly(2-methylpentamethylene        hexanediamide/hexamethylene hexanediamide/) (PA D6/66),        poly(decamethylene decanediamide) (PA1010), poly(decamethylene        dodecanediamide) (PA1012), poly(decamethylene        decanediamide/decamethylene terephthalamide) (PA1010/10T)        poly(decamethylene decanediamide/dodecamethylene        decanediamide/decamethylene terephthalamide/dodecamethylene        terephthalamide (PA1010/1210/10T/12T),        poly(11-aminoundecanamide) (PA11),        poly(11-aminoundecanamide/tetramethylene terephthalamide)        (PA11/4T), poly(11-aminoundecanamide/hexamethylene        terephthalamide) (PA11/6T),        poly(11-aminoundecanamide/decamethylene terephthalamide)        (PA11/10T), poly(11-aminoundecanamide/dodecamethylene        terephthalamide) (PA11/12T), poly(12-aminododecanamide) (PA12),        poly(12-aminododecanamide/tetramethylene terephthalamide)        (PA12/4T), poly(12-aminododecanamide/hexamethylene        terephthalamide) (PA12/6T),        poly(12-aminododecanamide/decamethylene terephthalamide)        (PA12/10T) poly(dodecamethylene dodecanediamide) (PA1212),        poly(dodecamethylene dodecanediamide/dodecamethylene        dodecanediamide/dodecamethylene terephthalamide)) (PA1212/12T),        poly(hexamethylene hexadecanediamide) (PA616), and        poly(hexamethylene octadecanediamide) (PA618); Group (II)        polyamides having a melting point of at least 210° C., and        comprising an aliphatic polyamide selected from the group        consisting of poly(tetramethylene hexanediamide) (PA46),        poly(c-caprolactam) (PA 6), poly(hexamethylene        hexanediamide/(c-caprolactam/) (PA 66/6) poly(hexamethylene        hexanediamide) (PA 66), poly(hexamethylene        hexanediamide/hexamethylene decanediamide) (PA66/610),        poly(hexamethylene hexanediamide/hexamethylene dodecanediamide)        (PA66/612), poly(hexamethylene hexanediamide/decamethylene        decanediamide) (PA66/1010), poly(hexamethylene decanediamide)        (PA610), poly(hexamethylene dodecanediamide) (PA612),        poly(hexamethylene tetradecanediamide) (PA614), and        poly(tetramethylene hexanediamide/2-methylpentamethylene        hexanediamide) (PA46/D6); wherein within Group (II) Polyamides        are Group (IIA) Polyamides having a melting point of at least        210° C. and less than 230° C. and Group (IIB) Polyamides having        a melting point of 230° C. or greater;    -   Group (III) polyamides having a melting point of at least 230°        C., and comprising        -   (aa) about 20 to about 35 mole percent semiaromatic repeat            units derived from monomers selected from one or more of the            group consisting of:            -   (i) aromatic dicarboxylic acids having 8 to 20 carbon                atoms and aliphatic diamines having 4 to 20 carbon                atoms; and        -   (bb) about 65 to about 80 mole percent aliphatic repeat            units derived from monomers selected from one or more of the            group consisting of:        -   (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon            atoms and said aliphatic diamine having 4 to 20 carbon            atoms; and        -   (iii) a lactam and/or aminocarboxylic acid having 4 to 20            carbon atoms;    -   Group (IV) polyamides comprising        -   (cc) about 50 to about 95 mole percent semiaromatic repeat            units derived from monomers selected from one or more of the            group consisting of:        -   (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms            and aliphatic diamines having 4 to 20 carbon atoms; and        -   (dd) about 5 to about 50 mole percent aliphatic repeat units            derived from monomers selected from one or more of the group            consisting of:        -   (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon            atoms and said aliphatic diamine having 4 to 20 carbon            atoms; and        -   (iii) a lactam and/or aminocarboxylic acid having 4 to 20            carbon atoms;    -   Group (V) polyamides having a melting point of at least 260° C.,        comprising        -   (ee) greater than 95 mole percent semiaromatic repeat units            derived from monomers selected from one or more of the group            consisting of:        -   (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms            and aliphatic diamines having 4 to 20 carbon atoms; and        -   (ff) less than 5 mole percent aliphatic repeat units derived            from monomers selected from one or more of the group            consisting of:        -   (ii) an aliphatic dicarboxylic acid having 6 to 20 carbon            atoms and said aliphatic diamine having 4 to 20 carbon            atoms;        -   (iii) a lactam and/or aminocarboxylic acid having 4 to 20            carbon atoms; and    -   Group (VI) Polyamides having no melting point and selected from        the group consisting of poly(hexamethylene isophthalamide/l        hexamethylene terephthalamide) (61/6T) and poly(hexamethylene        isophthalamide/hexamethylene terephthalamide/hexamethylene        hexanediamide) (61/6T/66).

Group (I) polyamides may have semiaromatic repeat units to the extentthat the melting point is less than 210° C. and generally thesemiaromatic polyamides of the group have less than 40 mole percentsemiaromatic repeat units. Semiaromatic repeat units are defined asthose derived from monomers selected from one or more of the groupconsisting of: aromatic dicarboxylic acids having 8 to 20 carbon atomsand aliphatic diamines having 4 to 20 carbon atoms.

Another embodiment is a molded or extruded thermoplastic article whereinsaid polyamide resin is selected from Group (III) polyamides selectedfrom the group consisting of poly(tetramethylenehexanediamide/tetramethylene terephthalamide) (PA46/4T),poly(tetramethylene hexanediamide/hexamethylene terephthalamide)(PA46/6T), poly(tetramethylene hexanediamide/2-methylpentamethylenehexanediamide/decamethylene terephthalamide) PA46/D6/10T),poly(hexamethylene hexanediamide/hexamethylene terephthalamide)(PA66/6T), poly(hexamethylene hexanediamide/hexamethyleneisophthalamide/hexamethylene terephthalamide PA66/6I/6T, andpoly(hexamethylene hexanediamide/2-methylpentamethylenehexanediamide/hexamethylene terephthalamide (PA66/D6/6T); and a mostpreferred Group (III) polyamide is PA 66/6T.

Another embodiment is a molded or extruded thermoplastic article whereinsaid polyamide resin is selected from Group (IV) polyamides selectedfrom the group consisting of poly(tetramethyleneterephthalamide/hexamethylene hexanediamide) (PA4T/66),poly(tetramethylene terephthalamide/c-caprolactam) (PA4T/6),poly(tetramethylene terephthalamide/hexamethylene dodecanediamide)(PA4T/612), poly(tetramethylene terephthalamide/2-methylpentamethylenehexanediamide/hexamethylene hexanediamide) (PA4T/D6/66),poly(hexamethylene terephthalamide/2-methylpentamethyleneterephthalamide/hexamethylene hexanediamide) (PA6T/DT/66),poly(hexamethylene terephthalamide/hexamethylene hexanediamide) PA6T/66,poly(hexamethylene terephthalamide/hexamethylene decanediamide)(PA6T/610), poly(hexamethylene terephthalamide/hexamethylenetetradecanediamide) (PA6T/614), poly(nonamethyleneterephthalamide/nonamethylene decanediamide) (PA9T/910),poly(nonamethylene terephthalamide/nonamethylene dodecanediamide)(PA9T/912), poly(nonamethylene terephthalamide/11-aminoundecanamide)(PA9T/11), poly(nonamethylene terephthalamide/12-aminododecanamide)(PA9T/12), poly(decamethylene terephthalamide/11-aminoundecanamide) (PA10T/11), poly(decamethylene terephthalamide/12-aminododecanamide)(PA10T/12) poly(decamethylene terephthalamide/decamethylenedecanediamide) (PA10T/1010), poly(decamethyleneterephthalamide/decamethylene dodecanediamide) (PA10T/1012),poly(decamethylene terephthalamide/tetramethylene hexanediamide)(PA10T/46), poly(decamethylene terephthalamide/c-caprolactam) (PA10T/6),poly(decamethylene terephthalamide/hexamethylene hexanediamide)(PA10T/66), poly(dodecamethylene terephthalamide/dodecamethylenedodecanediamide) (PA12T/1212), poly(dodecamethyleneterephthalamide/k-caprolactam) (PA12T/6), and poly(dodecamethyleneterephthalamide/hexamethylene hexanediamide) (PA12T/66); and a mostpreferred Group (IV) polyamide is PA6T/66.

Another embodiment is a molded or extruded thermoplastic article whereinsaid polyamide resin is selected from Group (V) polyamides selected fromthe group consisting of poly(tetramethyleneterephthalamide/2-methylpentamethylene terephthalamide) PA4T/DT,poly(tetramethylene terephthalamide/hexamethylene terephthalamide)PA4T/6T, poly(tetramethylene terephthalamide/decamethyleneterephthalamide) PA4T/10T, poly(tetramethyleneterephthalamide/dodecamethylene terephthalamide) PA4T/12T,poly(tetramethylene terephthalamide/2-methylpentamethyleneterephthalamide/hexamethylene terephthalamide) (PA4T/DT/6T),poly(tetramethylene terephthalamide/hexamethyleneterephthalamide/2-methylpentamethylene terephthalamide) (PA4T/6T/DT),poly(hexamethylene terephthalamide/2-methylpentamethyleneterephthalamide) (PA6T/DT), poly(hexamethylenehexanediamide/hexamethylene isophthalamide) (PA 6T/6I),poly(hexamethylene terephthalamide/decamethylene terephthalamide)PA6T/10T, poly(hexamethylene terephthalamide/dodecamethyleneterephthalamide) (PA6T/12T), poly(hexamethyleneterephthalamide/2-methylpentamethyleneterephthalamide/poly(decamethylene terephthalamide) (PA6T/DT/10T),poly(hexamethylene terephthalamide/decamethyleneterephthalamide/dodecamethylene terephthalamide) (PA6T/10T/12T),poly(decamethylene terephthalamide) (PA100T), poly(decamethyleneterephthalamide/tetramethylene terephthalamide) (PA100T/4T),poly(decamethylene terephthalamide/2-methylpentamethyleneterephthalamide) (PA10T/DT), poly(decamethyleneterephthalamide/dodecamethylene terephthalamide) (PA10T/12T),poly(decamethylene terephthalamide/2-methylpentamethyleneterephthalamide/(decamethylene terephthalamide) (PA10T/DT/12T).poly(dodecamethylene terephthalamide) (PA12T), poly(dodecamethyleneterephthalamide)/tetramethylene terephthalamide) (PA12T/4T),poly(dodecamethylene terephthalamide)/hexamethylene terephthalamide)PA12T/6T, poly(dodecamethylene terephthalamide)/decamethyleneterephthalamide) (PA12T/10T), and poly(dodecamethyleneterephthalamide)/2-methylpentamethylene terephthalamide) (PA12T/DT); anda most preferred Group (V) Polyamide is PA6T/DT.

In various embodiments the polyamide is a Group (I) Polyamide, Group(II) Polyamide, Group (III) Polyamide, Group (IV) Polyamide, or Group(V) Polyamide, respectively.

The polyamides may also be blends of two or more polyamides. Preferredblends include those selected from the group consisting of Group (I) andGroup (II) Polyamides; Group (I) and Group (III) Polyamide, Group (II)and Group (III) Polyamides, Group (II) and Group (IV) Polyamides, Group(II) and Group (V) Polyamides, and Group (IV) and Group (V) Polyamides.

A preferred blend includes Group (II) and (V) Polyamides, and a specificpreferred blend includes poly(hexamethylene hexanediamide) (PA 66) andpoly(hexamethylene terephthalamide/2-methylpentamethyleneterephthalamide) (PA 6T/DT).

Another preferred blend includes Group (II) and Group (III) Polyamidesand a specific preferred blend includes poly(s-caprolactam) (PA6) andpoly(hexamethylene hexanediamide/hexamethylene terephthalamide(PA66/6T).

In various embodiments 29 to 89.5, 49 to 89.5, or 55 to 89.5 weightpercent of polyamide resin is present in the thermoplastic polyamidecomposition. Preferably 30 the polyamide resin is a semicrystallinepolyamide having a melting point and is preferably selected from Group(I) to Group (V) polyamides as disclosed above. In one embodiment thereis less than 5 weight percent polyphenylene oxide present in thethermoplastic composition, and in another, no polyphenylene oxide ispresent. Preferably the polyamide resin has a number average molecularweight of at least 5000, and preferably at least 10000 as determinedwith size exclusion chromatography in hexafluoroisopropanol.

Poly(amino acid)-polyol Compound

Component b) is a poly(amino acid)-polyol compound provided by reactingb1) one or more amino acids and b2) a polyepoxy compound.

Component b1) is 90 to 10 weight percent one or more amino acidsselected from the group consisting of primary amino acids and secondaryamino acids and combinations of these; said amino acid having no morethan one hydroxyl group. Preferably the amino acid has a number averagemolecular weight of less than or equal to about 1000, preferably lessthan 500 or 300, as determined by calculation of molecular weight of theamino acid; or, if the amino acid is an oligomeric material, asdetermined with size exclusion chromatography. Amino acids useful in theinvention include aliphatic amino acids and aromatic amino acids. In oneembodiment the amino acid is a primary amino acid. In another embodimentthe amino acid has no more than one carboxylic acid. Herein amino acidsmay include one hydroxyl group and multiple acids

The term “amino acid” includes salts and hydrates of amino acidsincluding hydrochlorides, acetates, phosphates, monohydrates, and sodiumand potassium salts.

Aliphatic amino acids include those selected from the group consistingof: N-methylglycine, DL-alanine, aminocyclohexanepropionic acid,2-aminoisobutyric acid, 2-aminobutyric acid, DL-valine, DL-tert-leucine,DL-norvaline, DL-isoleucine, DL-leucine, DL-norleucine,DL-2-aminocaprylic acid, beta-alanine, DL-3-aminoisobutyric acid,DL-3-aminobutyric acid, 4-aminobutyric acid, 5-aminovaleric acid,6-aminocaproic acid, 7-aminoheptanoic acids, 8-aminocaprylic acid,11-aminoundecanoic acid, 12-aminododecanoic acid, DL-serine,DL-isocerine, DL-homocerine, DL-threonine, DL-4-amino-3-hydroxybutyricacid, 1-amino-1-cyclopropanecarboxylic acid,1-amino-1-cyclopentanecarboxylic acid, 1-amino-1-cyclohexanecarboxylicacid, trans-4-(aminomethyl)-cyclohexanecarboxylic acid,2-amino-2-norbornanecarboxylic acid, DL-proline, DL-dipecanolic acid,nipecotic acid, DL-lysine, DL-aspartic acid, DL-glutamic acidmonohydrate, DL-2-aminoadipic acid, 3-aminoadipic acid,2,6-diaminopimelic acid, L-gamma-carboxyglutamic acid.

Aromatic amino acids include those selected from the group consistingof: 4-aminobenzoic acid, 3-aminobenzoic acid, 2-aminobenzoic acid,2-phenylglycine, 2,2-diphenylglycine, N-phenylglycine,N-(4-hydroxyphenyl)glycine, DL-phenylalanine,alpha-methyl-DL-phenylalanine, DL-homophenylalanine,DL-2-fluorophenylglycine, DL-2-fluorphenylalanine,D-4-hydroxyphenylglycine, DL-tyrocine, 4-amino-DL-phenylalanine hydrate,DL-alpha-methyltyrosine, o-benzyl-L-tyrosine, and N-tritylglycine,

In one embodiment the amino acid is selected from the group consistingof 6-aminohexanoic acid, lysine, 11-aminoundecanoic acid, 4-aminobenzoicacid; and salts of these compounds.

Component b2) is 10 to 90 weight percent of a polyepoxy compoundcomprising at least two or more epoxy groups; the polyepoxy compoundhaving a epoxide equivalent weight of 43 to 4000 g/equivalent asdetermined by calculation, or if the polyepoxy compound is an oligomer,by titration using ASTM D1652-11 method; and a number average molecularweight (M_(n)) of less than 8000. In various embodiments the M_(n) isless than 2000, less than 1000, and less than 400. Preferably thepolyepoxy compound has a M_(n) of less than 1000.

Examples of the polyepoxy compounds useful in the invention include1,4-butanediol diglycidyl ether (BDE), bisphenol A diglycidyl ether(BADGE), bisphenol F diglycidyl ether (BFDE), trimethylolpropanetriglycidyl ether (TTE), hydrogenated bisphenol A type epoxy resin,brominated epoxy resin, cycloaliphatic epoxy resin, and glycidyl aminetype epoxy resin. Further examples of polyepoxides which can be used inthe present invention include polyepoxides made by epoxidation ofpolyenes such as 1,3-butadiene diepoxide (MW 86.09, epoxy equivalentweight=43.05), 1,2,7,8-diepoxyoctane, 1,2,5,6-diepoxycyclooctane,4-vinyl-1-cyclohexene diepoxide, and epoxidized polyisoprene copolymerssuch as commercial resins available from Shell Chemical Company, e.g.,EKP 206 and EKP 207 (MW 6,000, epoxy equivalent weight 670). Otheruseful polyepoxides are the EPON™ Resins, derived from a liquid epoxyresin and bisphenol-A, available from Momentive, Inc., Columbus, Ohio.The epoxy resin is not limited to these, and these may be used singly orin a combination of two or more kinds. In a preferred embodiment thepolyepoxy compound is trimethylolpropane triglycidyl ether (TTE).

Preferably b) the poly(amino acid)-polyol compound is present at 0.5 to8.0 weight percent, 1.0 to 4.0 weight percent and 1.0 to 3.0 weightpercent, in the thermoplastic melt-mixed composition.

By “reacting” means providing conditions such that one or morecarboxylic acid functionality or amino functionality, reacts with one ormore epoxy group of the polyepoxy compound to form an ester (C—O—C(O)—C)linkage and/or amino linkage (C—N—C) via ring-opening of the epoxyfunctionality. The ring-opening reaction also provides an equivalent ofhydroxyl group for each polyester link and/or amino link formed. Herein,the reaction product is referred to as “poly(amino-acid)-polyolcompound.” The reacting may be accomplished by mixing and heating acombination of polyepoxy and amino acids to a reaction temperature for areaction period to provide a desired percent conversion of the polyepoxyto poly(amino-acid)-polyol compound.

The percent epoxy conversion of the polyepoxy compound may be isdetermined by measuring the ¹H NMR signal of one of the epoxy ringhydrogen diastereomers versus a second internal standard signal thatdoes not change during the reaction. Thus, the reaction of selectedpolyepoxy and amino acids in the absence of polyamide resin can be usedto empirically determine the propensity for a selected polyepoxy/aminoacid composition to gel. Gelling, that is, cross-linking, is undesirableas the viscosity of the composition increases rapidly to the point wherethe composition may not be processible.

Suitable reaction temperatures include the range of 23° C. to 250° C.Suitable reaction periods include the range of 2 minutes to about 24hours. As desired by the artisan, the reaction may be performed: under arange of pressure, for instance 2 atmospheres to about 0.01 mm Hg; inthe presence or absence of a catalysis, e.g. acid catalysis or basecatalysis; and in the presence or absence of a solvent; in the presenceor absence of a plasticizer, or other additive that may be ultimatelyfound desirable in the thermoplastic melt-mixed composition. In oneembodiment the reaction is performed in the absence of a catalyst.

Reacting the combination of the polyepoxy compound (b2) and the aminoacid b2) provides a poly(amino-acid)-polyol compound having a range ofat least 10 percent conversion of epoxy equivalents of component (b1) upto, but excluding, the gel point of the components b1) and b2) asdetermined with ¹H NMR analysis. In one embodiment thepoly(amino-acid)-polyol compound has a M_(n) of at least 200 to about10000 as determined with size exclusion chromatography. In variousembodiments the poly(amino-acid)-polyol compound has a M_(n) of 400 toabout 8000 and 800 to about 8000. In various embodiments thepoly(amino-acid)-polyol compound has preferred ranges of at least 25percent conversion, 40 percent conversion, 50 percent conversion, 80percent conversion and 85 percent conversion, of epoxy groups incomponent b1) up to, but excluding, the gel point of the components b1)and b2).

Various embodiments include many combinations of polyepoxy compound b2)and amino acid b1) that provide a poly(amino-acid)-polyol compound thatcan be taken to 100% epoxy conversion without providing a gel point.

The upper limit of the extent of reaction of b2) polyepoxy compound andb1) amino acid to provide a useful reaction product is just below thegel point. The gel point is the point wherein the material iscrosslinked and can no longer flow and be melt-blended to provide auniform blend. The gel point can be calculated using a 15 modifiedCarothers equation (G. Odian, Principles of Polymerization, 1981, ISBN0-471-05146-2, John Wiley & Sons, Inc., p. 117-119) which is astatistical equation for nonequivalent (nonstoichiometric) reactantmixtures for 2 reagents, having at least 2 reactive groups A and B permolecule and at least one having more than 2 groups per molecule:

pc=1/{r[1+(fA−2)][1+(fB−2)]}exp1/2  Eq. (I)

where:pc=conversion of group A at gel point, conversion of group B is r×pcr=1 or <1, ratio of A to B groupsf>2 is a functionality of the reagent with functionality>2.

Examples of gel points (G-1-G-6), calculated using Eq (I) for variouscombinations of reagent functionality are listed in Table A.

TABLE A Gel point examples G1 G2 G3 G4 G5 G6 Reagent A (polyepoxy) 4 4 66 4 6 functionality (fA) Reagent B (aminoacid) 2 2 2 2 4 6 functionality(fB) Molar ratio of A to B reagents 0.5 0.25 0.33 0.083 1 0.5 Molar (orequivalent) ratio 1 0.5 1 0.5 1 0.5 of A to B groups (r) Gel Point (pcfor conversion 0.577 0.816 0.447 0.894 0.333 0.283 of group A, from Eq.1)

In a preferred embodiment the ratio of b1) amino acid to b2) polyepoxycompound is such that the ratio of amine and carboxyl groups to epoxygroup is in the range of 0.1 to 200, and more preferably 1.1 to 200(excess amino acid). The ratio is determined by dividing the amount ofeach reagent used by the equivalent weight of the polyepoxy compound andthe amino acid compound, respectively.

In a preferred embodiment the poly(amino-acid)-polyol compound b) has aM_(n) of at least 200 to 10,000 or 400 to 10000, or 400 to 8000, asdetermined with size exclusion chromatography.

The thermoplastic melt-mixed composition comprises 10 to about 60 weightpercent, and preferably 12.5 to 55, and 15 to 50 weight percent, of oneor more reinforcement agents. The reinforcement agent may be any filler,but is preferably selected from the group consisting calcium carbonate,glass fibers with circular and noncircular cross-section, glass flakes,glass beads, carbon fibers, talc, mica, wollastonite, calcined clay,kaolin, diatomite, magnesium sulfate, magnesium silicate, bariumsulfate, titanium dioxide, sodium aluminum carbonate, barium ferrite,potassium titanate and mixtures thereof. In preferred embodiments thereinforcing agent is selected from the group consisting of glass fiberand glass fiber with noncircular cross-section. The glass fiber may havesizing or coupling agents, organic or inorganic materials that improvethe bonding between glass and the polyamide resin.

Glass fibers with noncircular cross-section refer to glass fiber havinga cross section having a major axis lying perpendicular to alongitudinal direction of the glass fiber and corresponding to thelongest linear distance in the cross section. The non-circular crosssection has a minor axis corresponding to the longest linear distance inthe cross section in a direction perpendicular to the major axis. Thenon-circular cross section of the fiber may have a variety of shapesincluding a cocoon-type (figure-eight) shape, a rectangular shape; anelliptical shape; a roughly triangular shape; a polygonal shape; and anoblong shape. As will be understood by those skilled in the art, thecross section may have other shapes. The ratio of the length of themajor axis to that of the minor access is preferably between about 1.5:1and about 6:1. The ratio is more preferably between about 2:1 and 5:1and yet more preferably between about 3:1 to about 4:1. Suitable glassfiber are disclosed in EP 0 190 001 and EP 0 196 194.

The thermoplastic melt-mixed composition, optionally, comprises 0 to 30weight percent of a polymeric toughener comprising a reactive functionalgroup and/or a metal salt of a carboxylic acid. In one embodiment thecomposition comprises 2 to 20 weight percent polymeric toughenerselected from the group consisting of: a copolymer of ethylene, glycidyl(meth)acrylate, and optionally one or more (meth)acrylate esters; anethylene/α-olefin or ethylene/α-olefin/diene is copolymer grafted withan unsaturated carboxylic anhydride; a copolymer of ethylene,2-isocyanatoethyl (meth)acrylate, and optionally one or more(meth)acrylate esters; and a copolymer of ethylene and acrylic acidreacted with a Zn, Li, Mg or Mn compound to form the correspondingionomer.

The thermoplastic composition of the present invention may also comprise0 to 10 weight percent further additives commonly used in the art, suchas further heat stabilizers or antioxidants referred to as“co-stabilizers”, antistatic agents, blowing agents, plasticizers,lubricants and colorant and pigments. In one embodiment 0.02 to 0.5weight percent of one or more lubricants is present. In anotherembodiment 0.1 to 3.0 weight percent of one or more colorants ispresent; wherein the weight percent colorant includes the weight of thecarrier accompanying the colorant. In one embodiment the colorant isselected from the group of carbon black and nigrosine black pigment.

Co-stabilizers include copper stabilizers, secondary aryl amines,hindered amine light stabilizers (HALS), hindered phenols, and mixturesthereof, that are disclosed in US patent application publication2010/0029819, Palmer et al, herein incorporated by reference.

All preferred embodiments disclosed above for the thermoplasticmelt-mixed compositions are applicable to the processes and methods forpreparing the thermoplastic melt-mixed compositions disclosed herein.

Another embodiment is a process for providing a thermoplastic melt-mixedcomposition comprising:

-   -   A) melt-blending:    -   a) 15 to 89.5 weight percent of a polyamide resin;    -   b) 0.5 to 10 weight percent of a poly(amino acid)-polyol        compound provided by reacting:        -   b1) 90 to 10 weight percent one or more amino acids selected            from the group consisting of primary amino acids and            secondary amino acids and combinations of these; said amino            acid having no more than one hydroxyl group; and        -   b2) 10 to 90 weight percent of one or more polyepoxy            compound comprising at least two or more epoxy groups; the            polyepoxy compound having a epoxide equivalent weight of 43            to 4000 g/equivalent as determined by calculation, or if the            polyepoxy compound is an oligomer, by titration using ASTM            D1652-11 method; and a number average molecular weight            (M_(n)) of less than 8000;    -   c) 10 to 60 weight percent of reinforcing agent;    -   d) 0 to 30 weight percent polymeric toughener; and    -   e) 0 to 10 weight percent further additives;        to provide said thermoplastic melt-mixed composition; wherein        the weight percent of b) is based on the total weight of b1) and        b2); said poly(amino acid)-polyol compound having a range of at        least 10 percent conversion of epoxy equivalents of component        b1) up to, but excluding, the gel point of the components b1)        and b2) as determined with ¹H NMR analysis of the poly(amino        acid)-polyol compound

In another embodiment the above disclosed process further comprises thestep B) extruding strands of the thermoplastic melt-mixed compositionand chopping the strands to provide pellets.

Herein the thermoplastic composition is a mixture by melt-blending, inwhich all polymeric ingredients are adequately mixed, and allnon-polymeric ingredients are adequately dispersed in a polymer matrix.Any melt-blending method may be used for mixing polymeric ingredientsand non-polymeric ingredients of the present invention. For example,polymeric ingredients and non-polymeric ingredients may be fed into amelt mixer, such as single screw extruder or twin screw extruder,agitator, single screw or twin screw kneader, or Banbury mixer, and theaddition step may be addition of all ingredients at once or gradualaddition in batches. When the polymeric ingredient and non-polymericingredient are gradually added in batches, a part of the polymericingredients and/or non-polymeric ingredients is first added, and then ismelt-mixed with the remaining polymeric ingredients and non-polymericingredients that are subsequently added, until an adequately mixedcomposition is obtained. If a reinforcing filler presents a longphysical shape (for example, a long glass fiber), drawing extrusionmolding may be used to prepare a reinforced composition.

In preferred embodiments the thermoplastic melt-mixed compositionsdisclosed above have a melt viscosity at a hold time of 25 minutes lessthan 600% and preferably less than 300, 200, and most preferably, lessthan 130%, of the melt viscosity at a hold time of 5 minutes; asmeasured at temperature 10° C. to 30° C. above the melting point of thepolyamide resin, in a capillary reohmeter at a shear rate of 1000 sec⁻¹according to ASTM D3835.

The melt-mixed compositions, as disclosed above, are useful inincreasing long-term thermal stability at high temperatures of molded orextruded articles made therefrom. The long-term heat stability of thearticles can be assessed by exposure (air oven ageing) of 2 mm thicktest samples at various test temperatures in an oven for various testperiods of time. The oven test temperatures for the compositionsdisclosed herein may be 170° C. and 500, 1000, or 2000 hours testperiods; 210° C. and 500 or 1000 hours test periods; and 230° C. and 500or 1000 hours test periods. The test samples, after air oven ageing, aretested for tensile strength and elongation to break, according to ISO527-2/1BA test method; and compared with unexposed controls havingidentical composition and shape, that are dry as molded (DAM). Thecomparison with the DAM controls provides the retention of tensilestrength and/or retention of elongation to break, and thus the variouscompositions can be assessed as to long-term heat stability performance.

Another embodiment is a method for improving tensile strength retentionof a thermoplastic melt-mixed composition under air oven ageing (AOA)conditions comprising:

-   -   melt-blending:    -   a) 15 to 89.5 weight percent of a polyamide resin;    -   b) 0.5 to 10 weight percent of a poly(amino acid)-polyol        compound provided by reacting:        -   b1) 90 to 10 weight percent one or more amino acids selected            from the group consisting of primary amino acids and            secondary amino acids and combinations of these; said amino            acid having no more than one hydroxyl group; and        -   b2) 10 to 90 weight percent of one or more polyepoxy            compound comprising at least two or more epoxy groups; the            polyepoxy compound having a epoxide equivalent weight of 43            to 4000 g/equivalent as determined by calculation, or if the            polyepoxy compound is an oligomer, by titration using ASTM            01652-11 method; and a number average molecular weight            (M_(n)) of less than 8000;    -   c) 10 to 60 weight percent of reinforcing agent;    -   d) 0 to 30 weight percent polymeric toughener; and    -   e) 0 to 10 weight percent further additives;    -   to provide said thermoplastic melt-mixed composition; wherein        the weight percent of b) is based on the total weight of b1) and        b2); said poly(amino acid)-polyol compound having a range of at        least 10 percent conversion of epoxy equivalents of        component (a) up to, but excluding, the gel point of the        components a) and b) as determined with ¹H NMR analysis of the        poly(amino acid)-polyol compound; wherein 2 mm thick test bars,        prepared from said melt-mixed composition and tested according        to ISO 527-2/1BA, and exposed at a test temperature of 230° C.        for a test period of 1000 hours, in an atmosphere of air, have        on average, a retention of tensile strength of at least 25        percent, as compared with that of an unexposed control of        identical composition and shape; and wherein the polyamide resin        comprises a one or more polyamides selected from the group        consisting of Group (IIB) Polyamides, Group (III) Polyamides,        Group (IV) Polyamides, Group (V) Polyamides, as defined herein

One embodiment is a molded or extruded thermoplastic article comprisingthe thermoplastic melt-mixed composition as disclosed in the above,wherein the polyamide resin comprises one or more Group (I) Polyamides,wherein 2 mm thick test bars, prepared from said melt-mixed compositionand tested according to ISO 527-2/1BA, and exposed at a test temperatureof 170° C. for a test period of 500 hours, in an atmosphere of air, haveon average, a retention of tensile strength of at least 40 percent, andpreferably at least 50, 60, 70, 80, and 90%, as compared with that of anunexposed control of identical composition and shape.

One embodiment is a molded or extruded thermoplastic article comprisingthe thermoplastic melt-mixed composition, as disclosed in the aboveembodiments, wherein the polyamide resin comprises one or more Group(II) Polyamides, wherein 2 mm thick test bars, prepared from saidmelt-mixed composition and tested according to ISO 527-2/1BA, andexposed at a test temperature of 210° C. for a test period of 500 hours,in an atmosphere of air, have on average, a retention of tensilestrength of at least 40 percent, and preferably at least 50, 60, 70, 80,and 90%, as compared with that of an unexposed control of identicalcomposition and shape.

One embodiment is a molded or extruded thermoplastic article comprisingthe thermoplastic melt-mixed composition, as disclosed in the aboveembodiments, wherein the polyamide resin comprises a one or morepolyamides selected from the group consisting of Group (IIB) Polyamides,Group (III) Polyamides, Group (IV) Polyamides, Group (V) Polyamides, andGroup (VI) Polyamides, wherein 2 mm thick test bars, prepared from saidmelt-mixed composition and tested according to ISO 527-2/1BA, andexposed at a test temperature of 230° C. for a test period of 1000hours, in an atmosphere of air, have on average, a retention of tensilestrength of at least 25 percent, and preferably at least 40, 50, 60, 70,80, and 90%, as compared with that of an unexposed control of identicalcomposition and shape.

In another aspect, the present invention relates to a method formanufacturing an article by shaping the thermoplastic polyamidecomposition disclosed herein. Examples of articles are films orlaminates, automotive parts or engine parts or electrical/electronicsparts. By “shaping”, it is meant any shaping technique, such as forexample extrusion, injection molding, thermoform molding, compressionmolding or blow molding. Preferably, the article is shaped by injectionmolding or blow molding.

The molded or extruded thermoplastic articles disclosed herein may haveapplication in many vehicular components that meet one or more of thefollowing requirements: high impact requirements; significant weightreduction (over conventional metals, for instance); resistance to hightemperature; resistance to oil environment; resistance to chemicalagents such as coolants; and noise reduction allowing more compact andintegrated design. Specific molded or extruded thermoplastic articlesare selected from the group consisting of charge air coolers (CAC);cylinder head covers (CHC); oil pans; engine cooling systems, includingthermostat and heater housings and coolant pumps; exhaust systemsincluding mufflers and housings for catalytic converters; air intakemanifolds (AIM); and timing chain belt front covers. As an illustrativeexample of desired mechanical resistance against long-term hightemperature exposure, a charge air cooler can be mentioned. A charge aircooler is a part of the radiator of a vehicle that improves enginecombustion efficiency. Charge air coolers reduce the charge airtemperature and increase the density of the air after compression in theturbocharger thus allowing more air to enter into the cylinders toimprove engine efficiency. Since the temperature of the incoming air canbe more than 200° C. when it enters the charge air cooler, it isrequired that this part be made out of a composition maintaining goodmechanical properties under high temperatures for an extended period oftime. Also it is very desirable to have a shaped article that exhibitsno whitening or very little whitening upon aging.

The present invention is further illustrated by the following examples.It should be understood that the following examples are for illustrationpurposes only, and are not used to limit the present invention thereto.

Methods Compounding Methods

All Examples and Comparative Examples were prepared by melt blending theingredients listed in the Table in a 30 mm twin screw extruder (ZSK 30by Coperion) operating at about 280° C. for PA66 compositions, using ascrew speed of about 300-400 rpm, a throughput of 30-40 lb/h (13.6-18.1kg/h) and a melt temperature measured by hand of about 320-355° C. forall compositions. The glass fibers were added to the melt through ascrew side feeder. All other ingredients were added at the beginning ofthe extruder except as noted in Methods 1. Ingredient quantities shownin the Table are given in weight percent on the basis of the totalweight of the thermoplastic composition.

Method 1—A fraction (e.g. 500 g) of the polyamide was subjected tocryogenic grinding in a Bantam Micropulverizer to provide about 1millimeter average particle size particles. The poly(amino acid)-polyolwas blended into the ground particles to provide a uniform blend thatwas added via a powder feeder to the beginning of the extruder.

The compounded mixture was extruded in the form of laces or strands,cooled in a water bath, chopped into granules.

Mechanical Tensile Properties

Mechanical tensile properties, i.e. E-modulus, stress at break (Tensilestrength) and strain at break (elongation at break) were measuredaccording to ISO 527-2/1BA. Measurements were made on 2 mm thickinjection molded ISO tensile is bars at a testing speed of 5 mm/min.Mold temperature for PA 66 test specimens was 80° C.

Air Oven Ageing (AOA)

The test specimens were heat aged in a re-circulating air ovens (Heraeustype UT6060) according to the procedure detailed in ISO 2578. At variousheat aging times, the test specimens were removed from the oven, allowedto cool to room temperature and sealed into aluminum lined bags untilready for testing. The tensile mechanical properties were then measuredaccording to ISO 527 using a Zwick tensile instrument. The averagevalues obtained from 5 specimens are given in the Tables.

Melt Viscosity

Melt viscosity retention was determined at a hold time of 25 minutes ascompared to the melt viscosity at a hold time of 5 minutes; as measuredat temperature 10° C. to 30° C. above the melting point of the polyamideresin, in a capillary reohmeter (Kayness) at a shear rate of 1000 sec⁻¹according to ASTM D3835.

¹H NMR Method for Epoxy Conversion

The 1H spectra are recorded in CDCl₃ on Bruker 500 MHz NMR Spectrometeroperating at 500 MHz. The percent conversion of the epoxy functionalityin the polyepoxy compound is determined by measuring the ¹H NMR signalof one of the epoxy ring hydrogen diastereomers versus a second internalstandard signal that does not change during the reaction withpolyhydroxy compound. The ratio of the epoxy ring hydrogen signal to thestandard signal, adjusted for the moles of epoxy functionality andstandard in the starting composition, and number of hydrogens in thestandard signal, is used to determine the % conversion. For instance,with trimethylolpropane triglycidyl ether (TTE), the methyl group of theTTE is chosen as the internal standard signal (0.80 ppm) and one of theepoxy hydrogen diastereomers (2.55 ppm) is the epoxy signal measured.The following calculation provides the % conversion:

${{Epoxy}\mspace{14mu} {Conversion}\mspace{14mu} (\%)} = {100 - {\frac{{Area}\mspace{14mu} {peak}\mspace{14mu} {at}\mspace{14mu} 2.55\mspace{14mu} {ppm}\mspace{14mu} \left( {{{broad}\mspace{14mu} \underset{\_}{{CH}\; 2}},{{TTE}\mspace{14mu} {epoxy}\mspace{14mu} {ring}}} \right)}{{Area}\mspace{14mu} {peak}\mspace{14mu} {at}\mspace{14mu} 0.80\mspace{14mu} {ppm}\mspace{14mu} \left( {{{{broad}\mspace{14mu} \underset{\_}{{CH}\; 3}{CH}\; 2} -},{TTE}} \right)} \times 100}}$

In this case no adjustment of the ratio is needed as there are threeequivalent epoxy groups each having one equivalent diastereomer hydrogenand three equivalent methyl hydrogens in the internal standard.

Whitening Determination Method

Two 5 in×3 in×3 mm plaques were treated by placing in an environmentalchamber under conditions of 85% relative humidity and 85° C. After oneday one plaque was removed from the chamber and visually inspected. TheL value, determined at 110° reflection was measured with a ChromaVisionMA100 Multi-Angle Spectrophotometer (manufactured by X-Rite,Incorporated, Grandville, Mich.). L is a common measure of whiteness onthe CIELAB colorspace. The L value was measured at 4 places on theplaque, both front and back and the L values averaged. A determinationof L also was performed on an untreated plaque. A ΔL value wasdetermined by subtracting the average of the four L measurements of theuntreated plaque from the average of the four measurements from thetreated plaque. After 7 days, the second plaque was removed from thechamber and the L value and ΔL value determined.

Low L values correspond to darker plaques and higher L values correspondto lighter plaques. Therefore a positive ΔL means a change from darkerto lighter.

A survey found that, by visual observation, those of ordinary skill inthe art could identify three levels of whitening, listed in Table B,corresponding to the ΔL values determined by spectroscopic measurementsmeans. Thus, using this relationship in some examples, visualobservation was used to evaluate whitening where the L values could notbe conveniently measured.

TABLE B Characterization of Whitening Visual observation ΔL (110°) noneΔL < 5  slight  5 < ΔL < 15 moderate 15 < ΔL < 25 severe ΔL > 25

Materials

PA66 refers to an aliphatic polyamide made of 1,6-hexanedioic acid and1,6-hexamethylenediamine having a typical relative viscosity of 49 and amelting point of about 263° C., commercially available from E.I. DuPontde Nemours and Company, Wilmington, Del., USA under the trademark Zytel®101NC010 polyamide.

Glass fibers A refer NEG D187H glass fibers manufactured by NipponElectric Glass, Osaka, Japan.

Black Pigment A refers to ZYTEL® FE3786 BK031C black concentrate, a 40wt % nigrosine black pigment concentrate in a PA66 carrier.

Black Pigment B refers ZYTEL® FE3779 BK031C black concentrate, a 25 wt %carbon black in a PA6 carrier.

Cu heat stabilizer refers to a mixture of 7 parts of potassium iodideand 1 part of copper iodide in 0.5 part of aluminum stearate wax binder.

Kemamide E180 lubricant is N-stearylerucamide, CAS No. [10094-45-8],available from Chemtura Corp., Philadelphia, Pa.

TTE refers to trimethylolpropane triglycidyl ether from Sigma-Aldrich.

L-lysine was available from Aldrich Chemical Co.

LT31 (3 lysine+1 trimethyolpropanetriglycidyl ether) poly(aminoacid)-polyol: L-lysine (146 equivalent weight, 200 g, 1.368 mol) andethylene glycol (500 g) were combined in a reaction flask and heated to60° C. for 1.5 h under an atmosphere of nitrogen, until the L-lysinedissolved. TTE (302 equivalent weight, 138 g, 0.456 mol) was added dropwise (˜1-2 drops/sec) over 30 minutes to a stirred vortex of theL-lysine/ethylene glycol mixture. The mixture was stirred about 18 h at60° C., cooled to room temperature, and methanol (300 mL) added toprovide a solution. The solution was slowly added to 1.75 L of rapidlystirred tetrahydrofuran (THF) to precipitate the poly(aminoacid)-polyol. The supernatant was decanted and the precipitate treatedagain with methanol and THF to provide a purified solid precipitate thatwas collected and dried in vacuum at 80° C. Yield was 99%. The numberaverage molecular weight was 5381 (as determined with size exclusionchromatography based on PMMA standard) and polydispersity was 2.8.

EXAMPLES

TABLE 1 Example C-1 1 PA66 63.00 59.90 Glass Fiber A 35.00 35.00 Cu heatstabilizer 0.30 0.40 Black Pigment A 0.60 0.60 Black Pigment B 1.00 1.00Kemamide E180 0.10 0.10 LT31 (3 lysine + 1 trimethyolpropanetriglycidylether) 3.00 Tensile Properties, Dry-As-Molded Tensile Strength [MPa] 235246 Elongation [%] 5.0 4.9 Tensile Properties, 500 h at 230° C. TensileStrength [MPa] 70 215 Tensile Strength Retention [%] 30% 87% Elongation[%] 1.9 3.3 Elongation Retention [%] 37% 68% Tensile Properties, 1000 hat 230° C. Tensile Strength [MPa] 3 153 Tensile Strength Retention [%] 1% 62% Elongation [%] 0.3 3.0 Elongation Retention [%]  6% 61% MeltViscosity @ 290° C. MV @ 5 min 278 91.0 MV @ 25 min 210 14.0 % MVRetention 76% 15%

We claim:
 1. A thermoplastic melt-mixed composition comprising: a) 15 to89.5 weight percent of a poly(hexamethylene hexanediamide); b) 0.5 to 10weight percent of a poly(amino acid)-polyol compound provided byreacting: b1) 90 to 10 weight percent one or more amino acids selectedfrom the group consisting of primary amino acids and secondary aminoacids and combinations of these; said amino acid having no more than onehydroxyl group; and b2) 10 to 90 weight percent of one or more polyepoxycompound comprising at least two or more epoxy groups; the polyepoxycompound having a epoxide equivalent weight of 43 to 4000 g/equivalentas determined by calculation, or if the polyepoxy compound is anoligomer, by titration using is ASTM D1652-11 method; and a numberaverage molecular weight (M_(n)) of less than 8000; wherein the weightpercent of component b) is based on the total weight of b1) and b2);said poly(amino acid)-polyol compound having a range of at least 10percent conversion of epoxy equivalents of component (b1) up to, butexcluding, the gel point of the components b1) and b2) as determinedwith ¹H NMR analysis of the poly(amino acid)-polyol; c) 10 to 60 weightpercent of reinforcing agent; d) 0 to 30 weight percent polymerictoughener; and e) 0 to 10 weight percent further additives; wherein theweight percentages a), b), c), d), and e) are based on the total weightof the thermoplastic melt-mixed composition.
 2. The thermoplasticmelt-mixed composition of claim 1 wherein the one or more amino acidshave a number average molecular weight of up to
 500. 3. Thethermoplastic melt-mixed composition of claim 1 wherein the poly(aminoacid)-polyol compound has a number average molecular weight of about 200to about
 10000. 4. The thermoplastic melt-mixed composition of claim 1wherein said poly(amino acid)-polyol compound has at least 25 percentconversion of epoxy equivalents.
 5. The thermoplastic melt-mixedcomposition of claim 1 wherein the amino acid is selected from the groupconsisting of 6-aminohexanoic acid, lysine, 11-aminoundecanoic acid,4-aminobenzoic acid; and salts of these compounds.
 6. The thermoplasticmelt-mixed composition of claim 1 wherein the polyepoxy compound is totrimethylolpropane triglycidyl ether.
 7. A molded or extruded articlemade from the thermoplastic melt-mixed composition of claim
 1. 8. Themolded or extruded thermoplastic article of claim 7 wherein 2 mm thickis test bars, prepared from said melt-mixed composition and testedaccording to ISO 527-2/1BA, and exposed at a test temperature of 230° C.for a test period of 500 hours, in an atmosphere of air, have onaverage, a retention of tensile strength of at least 25 percent, ascompared with that of an unexposed control of identical composition andshape.
 9. A process for providing a thermoplastic melt-mixed compositioncomprising: A) melt-blending: a) 15 to 89.5 weight percent ofpoly(hexamethylene hexanediamide); b) 0.5 to 10 weight percent of apoly(amino acid)-polyol compound provided by reacting: b1) 90 to 10weight percent one or more amino acids selected from the groupconsisting of primary amino acids and secondary amino acids andcombinations of these; said amino acid having no more than one hydroxylgroup; and b2) 10 to 90 weight percent of a polyepoxy compoundcomprising at least two or more epoxy groups; the polyepoxy compoundhaving a epoxide equivalent weight of 43 to 4000 g/equivalent asdetermined by calculation, or if the polyepoxy compound is an oligomer,by titration using ASTM D1652-11 method; and a number average molecularweight (M_(n)) of less than 8000; c) 10 to 60 weight percent ofreinforcing agent; d) 0 to 30 weight percent polymeric toughener; and e)0 to 10 weight percent further additives; to provide said thermoplasticmelt-mixed composition; wherein the weight percent of b) is based on thetotal weight of b1) and b2); said poly(amino acid)-polyol compoundhaving a range of at least 10 percent conversion of epoxy equivalents ofcomponent b1) up to, but excluding, the gel point of the components b1)and b2) as determined with ¹H NMR analysis of the poly(aminoacid)-polyol compound.